The mtDNA profiles of F-4 fighter pilots who perished in the late 1990s are known and available for comparison to individuals who are curious whether they may have descended from the same lineage. The story below outlines how the mtDNA profiles of the F-4 fighter pilots were discovered.
F-4 Fighter Pilot DNA
F-4 fighter planes are two-seater, twin engine, all weather, long-range planes that are regarded by many as one of the best military aircraft designs of all time. The legendary F-4 Phantoms were introduced in 1958 and although they have been retired from the United States Air Force and Navy, they are still in use elsewhere around the world.
Several accidents have occurred during the extensive pilot training required for the F-4 Phantoms, not to mention the losses during armed combats. The worst non-combat accident occurred in 1971 when an F-4 Phantom crashed into a passenger flight over southern California. All 49 passengers and crew on the passenger flight were killed, along with the F-4 pilot. The radar intercept officer was able to eject from the F-4 Phantom and parachute to safety.
In the late 1990s, a plane crash between two training F-4 Phantoms near Japan resulted in the traumatic death of the two pilots. Their bodies disintegrated as they fell into the ocean, preventing any chance of identification using dental records and body features. Instead, several tissue fragments recovered from the crash area were analyzed by genetic techniques to quickly confirm the identification of the victims.
Determining the blood type
Blood typing is a useful technique for the preliminary analysis of unknown remains and bloodstains. An individual’s ABO blood group is often determined by serological techniques, which detect the different antigens present on the surface of red blood cells. However, this technique may not be as accurate for degraded tissue samples. Genetic analysis of the blood type specific glycosyltransferase gene is an alternative approach to determine a blood type, and this technique was used for the analysis of the plane crash victims.
The parents of one victim from the Japanese crash (pilot 1) were typed as OO and BO, while the parents of the second victim (pilot 2) were AB and OO. Of the multiple human fragments from the crash site, several were typed as BO (and hence match that expected for pilot 1), while the other tissue samples were AO (and match that expected for pilot 2). Blood typing is a useful initial analysis that can be used to exclude possible identities, but further analyses are required for conclusive results.
What further genetic analyses were conducted?
Autosomal short tandem repeat (STR) analysis is a useful technique for the identification of unknown remains, as only a small region of the DNA needs to be amplified and analyzed. Nine STR markers were analyzed from the tissue samples and the parents of the missing pilots. We inherit one autosomal marker from each parent, hence inheriting a mix of both of our parents’ autosomal chromosomes. The STR profiles from the tissue samples were as expected for a child of each the two parent sets, further supporting the blood typing analysis described above.
Mitochondrial DNA (mtDNA) differs from autosomal DNA, in that it is strictly maternally inherited (mother to child). There are hundreds of copies of the mtDNA genome in each of our cells, making this DNA type very useful for the analysis of degraded tissue samples. A hypervariable region (HVR1) was sequenced from each tissue and parent sample. As expected, the tissue samples assumed to be from pilot 1 matched the mother of pilot 1, while the tissue fragments assumed to be from pilot 2 matched the mother of pilot 2.
These blood type genotyping, autosomal STR and mtDNA analyses have confirmed that the remains recovered from the sea do belong to the two pilots who were thought to have been killed in this horrific midair plane crash. This study reinforces the benefits of genetic techniques for the analysis of fragmented remains, as often occurs in disastrous plane and traffic accidents. Typical identification techniques that rely on dental records, body features or Y-rays are not possible with destroyed and/or degraded remains, but genetics still often allow the remains to be conclusively identified.
DNA Database Comparisons
The DNA tests conducted in this study have defined the mtDNA profiles of two training F-4 fighter pilots, who died in a horrible crash over the sea near Japan. This study required the testing of family members for positive identification because there was no DNA present for the pilots for direct comparison, which would have provided a faster and even more conclusive result. It is now becoming increasingly popular to bank DNA samples for testing at a later date. Such applications include saving DNA for disease testing for the benefit of future generations, saving DNA for identification purposes in the event of disaster or saving DNA to preserve the integrity of the family tree and for inheritance purposes to conclusively determine biological relationships. More information about DNA banking can be found at www.securigene.com.